Thanks for the kind comments. The blobs flow because they're done with a so-called metaball shader: for each pixel in screen, it's distance to the blobs is calculated and that info is used to color that pixel.
From the lua-side of things, the game sends position, color and radius data about the blobs to a pixel shader, which calculates the effect (the blobs are fully drawn in that one shader).
Here's a small love-file to demo that a bit better (only the drawing is demonstrated). Feel free to unzip and look into the code: goo.gl/ob3Vcx